<!DOCTYPE HTML>
<html>
<head>
    <title>CCXT Basic example for the browser</title>
    <script type="text/javascript" src="https://unpkg.com/ccxt"></script>
    <style type="text/css">
        #contentA { background-color: #ccccff; }
        #contentB { background-color: #ffcccc; }
    </style>
    <script>'use strict'

        class MyExchange extends ccxt.gdax {

            async fetchTicker (symbol, params = {}) {
                alert ("I'm about to call the parent method from the overrided class, woohooo!")
                // just call the parent method and that's it
                return super.fetchTicker (symbol, params);
            }
        }

        document.addEventListener ("DOMContentLoaded", function () {

            const exchange = new MyExchange ()

            const symbol = 'ETH/BTC'

            const showFetchedTicker = function (ticker, elementId) {

                const text = [
                    exchange.id,
                    symbol,
                    JSON.stringify (ticker, undefined, '\n\t')
                ]

                document.getElementById (elementId).innerHTML = text.join (' ')

            }

            exchange.fetchTicker (symbol).then (ticker => showFetchedTicker (ticker, 'content'))
        })
    </script>
</head>
<body>
<h1>Hello, CCXT!</h1>
<pre id="content"></pre>
</body>
</html>